There is a concern over the presence of particulate contaminates, especially viable particulate contaminates, in a respirable gaseous medium such as air. This has created a need to know if the gaseous medium contains contaminates and especially those contaminates which are respirable. Such a respirable gaseous medium may be simply the non-pressurized ambient atmosphere or the output of a positive pressure device. Numerous devices are used which generate a positive pressure outflow of a respirable gaseous medium such as inhalation or respiratory therapy equipment, anesthesia administration equipment and infant life support devices including incubators. Many of these devices also produce an aerosol entrained in the gaseous medium which aerosol serves as an ideal carrier for viable particles.
While a number of prior art air samplers are available for particle sampling of ambient air, none of these samplers are adapted to sample air or other gaseous mediums from a positive pressure delivery device such as those described above. Moreover, these prior art samplers must be reused in order to be economically feasible but this requires sterilization and additional handling between uses thereby increasing the likelihood of initial contamination of the sampler prior to the subsequent sampling operation. These prior art samplers have also used several stages which classified the air-borne particles into a like number of classes. In most instances, however, the information desired is whether the particles are sufficiently small to be inhaled and achieve lung penetration. The attempts to classify the particles as taught by the prior art into several classes has resulted in partial commingling of the classes so that the resulting readings were confusing.